Method for polymerizing chlorotrifluoroethylene



Patented Oct. 7, 1952 METHOD FOR POLYMERIZING CHLORO- TRIFLUOROETHYLENEGeorge F. Roedel, Schenectady, N. Y., assignor to .General ElectricCompany, a corporation of v New York No Drawing. I Application June 28,1950,

Serial No. 170,940 v Claims. (c1. zoo-92.1)

Thisinventionis concerned with a method for making polymericchlorotrifiuoroethylene. More particularly,v the invention is'concernedwith a process for making high molecular weight, sub.- stantiallyheat-stable polymeric chlorotrifluo'ro ethylene which comprises(1)-forming an aqueous suspension or a mixture of ingredient having apH-below 4.0 and comprising (a) chlorotrifiuoroethylene, (b) water tc)an organic peroxidepolymerization catalyst; (d) a heavy metal compoundwhose metal ion'is capable of existing in at least two-valence statesand which compound is soluble in the chlorotrifluoroethylene. e. g., amonomer-soluble iron='salt',-(e) a water-soluble reducing' agent readilyoxidized in the presence of the polymerization-catalyst and theaforesaid heavy metal compound and (2) effecting reaction between theingredients at a temperature below C. while agitating the mixture ofingredients;

One of the objects of this invention is to prepare polymericchlorotrifluoroethylene.

A further object of the invention is to obtain polymericchlorotrifluoroethylene in good yields. Another object of the inventionis to obtain polymeric chlorotrifluoroethylene having a high softeningpointatleast above 220 C; "A still furtherobject of this invention is toobtain polymeric 'chlorotrifluoroethylene in. a finely dividediorm-Iwhich can be advantageously employed for various applications.

' It has been, known heretofore that polymeric chlorotrifiuoroethylenecouldbe prepared by polyf merizing the monomer in bulk using variouspolymerization catalysts. However, such methods have the disadvantage ofrequiring substantially long. periodsoftime and in addition giverelatively low yieldsor conversions of the initial monomer.

It has also beengsuggested that chlorotrifluoroethylene canbecopolymerized with, for example,

ethylene in aqueous emulsions to ive polymers corded softening point ofabout 145-160 C. ,(as

disclosed in U. S. Patent 2,392,378) or the chlorotrifiuoroethylenehomopolymer obtained by polymerizationof the-monomer in aqueousemulsion.

However, such a low softening point for polymericchlorotrifiuoroethylene renders the product of questionableutility inview of the fact that materials can be prepared having softening pointshigher; than the recorded softening point for-the ing points well below200 C.,while at thesame .4 whose softeningipoints are higher than there- :2 time introducing contaminants in the polymer which are difiicultto remove. a I r I have now discovered unexpectedly that by employing aparticular combination of conditions of reaction I am able to obtainfrom the monomeric chlorotrifluoroethylene good yields of the polymerwhose properties are more than satisfactory, espe v cially polymerswhose softeningpoints are above 220 C., e. g., from 220 to 270 C. orhigher, and which under pressure sinter to clearspeci'mens at 220 to 230C. These results are obtained by conducting the polymerization of thechlorotrifiuoroethylene in the form of an aqueous suspension using aparticular combination of ingredients" and a particular ratio of suchingredients while main taining the pH of the system within a fairlynarrow range. V l a The first condition which is necessary for thepractice of my invention is that the reaction be conducted in the formof an aqueous suspension. In preparing the suspension of thecholorotrifiuoroethylene, the ratio of water to monomer is preferablyvaried within certain limits. Thus, on a weight'basisl may .use a ratiogreater than 1; and up to Her more parts water per part of monomericchlorotrifluoroethylene.-v The ratio of water is critical and I havefound that thewater should be present in a-ratio greater than 1 to 1,for ex-. ample, from about 2 to 6 parts. of water per part of monomer.Below a ratio of 2 parts water per part monomer, .the rate of conversionof .the monomer to the polymer decreases rapidly. Ithas also been foundthat at a ratio of around 5and over parts water per part monomer, stablewater.- wet suspensions or latices-are unexpectedly obtained withconversions of the monomer to polymer above Where the water-to-monomerratio is lower than 5 to 1, water-wet suspensions can be-obtained onlyby stopping the reaction at the point which gives around 15 to 16%solids content. With water ratios below 5 to land where the solidscontent exceeds about 16%, the polymer is obtained as a non-water-wetpowder. It will, of course, be apparent that although larger amounts ofwater may be used, excess amounts of water may not be advantageous undersome circumstances since it'will requireflarg er reaction vessels andgreater handling than "where the water-to-monomer ratio is within therange described above. This, however, does not mean that ratios of waterto monomer in excess or. for example, 2 to 1,'for instance, 6 tol, ormore,"m'ay not be used, and I do no'tintend to be limited'in respect toupper rangesof water-to-monomer t s Q I; I.

polymerization catalystand heavy metal compound, e. g., the iron salt oriron promoter. Various reducing agents may be employed as, for example,sodium bisulfite, potassium bisulfite, sodium hydrosulfite; otheroxidizable sulfoxy and sulfur containing compounds, e. g., sulfurousacid, sulfites, hydrosulfites, thiosulfates, sulfides sulfoxalates etc.The amount of the reducing agent may be varied, for instance, from about0.005 to 1%, by weight, or more based on the weight of Water and is notcritical though it is preferably present in an amount ranging from about0.01 to 0.5%, by weight. Further examples of heavy metal compounds andreducingagents which may be employed in the redox system maybe found,forinstance, in U. S. Patents 2,380,473-477.

Throughout the reaction agitation isprefer- Since the monomericchlorotrifluoroethylene is a gas at normal temperatures and pressures,it is advantageous to conduct the reaction in a closed vessel undersuperatmospherie pressure.

I have found it satisfactory to operate the reac-,

tion under the autogenous pressure of the reactants in a closed vessel.As will be apparent to persons skilled in the art, the temperature ofpolymerization will determine the pressure of the system. Using thepreferred temperature ranges it will be-found that the-pressuresemployed will range from about 20-115'p. s. i. which is much lower thanhas heretofore been employed in the polymerization of the same orsimilar monomers. However, I do not intend. to be limited to-theseparticular pressures since as far as can be determined they are notparticularlycritical andunder many conditionsof reaction higherorlowerpressures may be employed without departing from the scope of theinvention. I

One of the most important advantages of my claimed process for preparingpolymeric chloro trifiuoroethylene resides in the fact that relativelylow temperatures can be employed as compared to other processes'involvedin the-polymerization of similar or difierent monomers which may requirerelatively higher temperatures. Thus, I may use temperatures ranging,for example, 'from about to 35 or 40 C.,preferably from about 0 to 30C., in which range the most advantageous utilization of the combinationof ingredients and conditions is realized. At temperatures above 40 or45 C., the catalyst decomposes too rapidly and tends to give lowmolecular' weight polymers having low softening points.

The time within which the reaction may be consummated can, of course, bevaried within wide limits depending, for example, on theconcentration-of water to monomer ratio, impurities and contaminationsof the reaction mass (which should be kept to. a minimum), rate ofagitation, redox system used,'concentration of heavy metal ion orcompound, temperature employed, etc. Generally, times of the order offrom about 5 to 50 or 60 hours, for example, from about 8 to 15 hours,are sufllcientwithin which to complete the reaction? 1 In order thatthose skilled in the art may better understand how the present inventionmay be practiced, theiollowing examples are given by the [reaction wasconducted in thesubstantial.

'Table I Sa npieA Sample Sample Chlorotrifluoroethyl ene.in parts; I

I 125 v125 Distilled Water .do.-- 125 250 375 t-Butyl Perbenzoata. do0.126 0.125 0. 125 NBHSO;.' d0 0. 075 0.075 0. 075 Soluble Iron Phosphat0.075 0. 075 0. 076

Pei-cent Yield;

This comprises iron phosphate containing a small amount-of citrate ionto effect solubilization of the iron phosphate in the chlorotrifluoroethylene. Each mixture of ingredients was charged to the Pyrexreaction vessel, frozen and evacuated to remove-air and oxygen, thereaction vessel closed and agitated by rocking ,for 24 hours at around25C. At the end of this time, the polymer was removed and weighed todeterminethe percent conversion of the monomer to, the polymer with! theresult shown in the above Table I. Each of the polymers hadhighsoftening points well above 200 0." H 1 "This example illustratesthe efiect of varying the pH of the system. More particularly, a mixtureof ingredients comprising 250 parts water; 125 partschlorotrifiuoroethylene, 0.3 part soluble iron phosphate, 0.3 part'so'dium' bisulfite' (NaHSOs), and 0.125 parttertiary butyi perben zoatewas charged to a reaction vessel similar to that employed in Exampleland the pH of this system was adjusted by adding standard solutions ofeither potassium hydroxide or hydrogen chloride. .The following tableshows the results of polymerizing the chlorotrifluoroethylene underEXAMPLE .3 v

In this example, 125 parts chlorotrifiuoroethylene, 250 parts water, 0.2part sodium bisulfite, 0.125 part tertiary butyl perbenzoate, 0.02 partferric benzoate '[Fe(CeH5CO2)s] and0.025- part potassium hydroxide toeifect a pH around 3.0, were mixed together in a Pyrex-reaction vessel,the latter closed and caused to react under autogenous pressure for 10hours at 250 C. At theend of this time it was found there was an 84 per.cent conversion to the polymer in the reaction vessel. When the pH ofthe system was raised or lowered by the addition of more orlesspotassium hydroxide, as, for example, the addition of either 0.0280 or0.0224 part KOI-I in place of the 0.025 part KOH used above, it wasfound 7; thatlthe percent conversion in the first. case: (0.028 partKOH) was about 11.4% andinthe. second case (0.0224part KOH) was about66.0%, thus indicating the critical effect of varying the DHasystemqemploying ferricbenzoate. Howevcr if adequate control is.maintained,.this sys: tem; produces polymers possessing very desirablecharacteristics with; regard. tohigh molecular" weight and clearness of.the. molded polymer.

Instead of adding the solubilizing organic acid in the form ofan ironsalt thereof, it may be introduced separately and formed in situ. Moreparticularly, using iron sulfate as an example, the latter may be causedto react with, for; example, benzoic acid to give the iron ben'zoate;

However. care must be taken to makesure'thatv any acid, for example,sulfuric or phosphoric acid (when using iron phosphate) formed asaresult, of such reaction is. neutralizedby means ofsome suitableneutralizingagent soth'at'the pH is maintained within the rangesdescribed previously. i

. This-example:illustrates; the effect of" varyingthe-concentration ofthe heavy metal compound, specifically an iron compound. Moreparticularly; amixture of ingredients comprising 7500'parts;chlorotrifiuoroethylene, 15,000 partswater, B parts; tertiarybutyl perbenzoate, and a mixtureof soluble iron phosphate (containing asmall amount of citrate ioniand'sodium bisulfite in the weight ratio of.1 to 4,,was reacted under pressurein a vessel similar to that employedin Examplel for 1.6 hours at 25 C. In each. case. of the following fivesample tests, 'the amount of soluble, iron phosphate varied so that the.soluble iron phosphate wasequal to from about 0.6 to'18 parts by weight,with the sodium bisulfite varied accordingly inthe l' to 4 ratiodescribed above. The following Table IIIshowsv the effect of thevariation of the soluble iron phosphate concentration:-

Table. I I I 7250535? Pew-em By Percent Chlorotri- 3 5 3: Conversionfluoroothylenc From the foregoing table; it is apparent that an optimumvalue 0L3 parts. ,so1ub1e iron phosphate (about 0.04%.. by weight) and12 parts sodium sulfite per 7500 parts monomer, gave the best yield ofpolymer.-

. EXAMBIJEjSf e In this, example thegeffectrofwvarying thearatim Qf;soluble: iron 9 hosphate to: sodium bisulfite is": illustrated byth,e-,.tests conducted. below... More: particularly, 250 parts distilledwater; 125.: parts. ohlorotrifluoroethylene, 0.0.5. partrtertiary butyl:perbenzoate. were-mixediwith the .following corresponding per cents,byxweight (based on .monomer), .of' soluble iron phosphate :and sodiumbil-- sulfi-teillustrated; below in:.: Table. IS/T, and... the: mixturescaused .to react at; 25?, 0;; withazagitation' for; about 163 hours;The: results;of;'suclr/variation. in the ratiouof .the. redoxxsystem:is; shown. imthe. table;below.;

TdbletIV" .Eercent; Soluble Iron Phosphate Percent Convertsion Percent 1NaHS Os 0. 0024 O. 0060 0.0125 Q; 025 0. O6

Chlorotrifiuoroethyie'ne 7.5 parts Water 54.5 parts Soluble ironphosphate flu. 0.003 part. Sodium bis'ulfite 0.012 part Tertiary butylperbenaoate' 0.0045 part (0.06%)

Hydrogen chloride 0.00182 (toa pH'of' This-system was heated'v withagitation at 25 C. foryabout 9 -hours., At the end of this time itwasfound thatthe -conversion had reached polymer; based on the charge;of monomer. The: polymer-had. a. softening point of 225 C;

It hasbeenfoundthat in some cases: lower concentrations ofperoxide.-or-polymerization accelerator can be employed, withacorrespondingimprovement in the properties of. the polymer obtained.It. has. also been found that by the: incremental addition of thepolymerization catalyst or initiator, for example; tertiary butylperbenzoate, it is possible=.to:- effect good conversion of the. monomerandalso obtain improved polymers of greatly increa'sed. molecularweight. The following Example 7' illustrates the eifect. of loweringithe peroxide concentration. As: will .be' shown. in. thesesexamples, greater conversion was.;obtained with larger amounts ofcatalyst.

However the: use .ofrlarger amounts. of. catalyst.

resulted in, somewhat lower molecular weight products, whereas thereductionof the-amountofcatalyst employed gave considerably higher mo.-lecular weight productsebut. also resulted. in. a. slowerconversionof.the monomer'to the polymer. Thiscanbe. overcome intsome cases by themore-- mental addition of the catalyst- To evaluatel the. quality of;thepolymer as evidencedby ,it's..molecular weight, the specificviscosity of-the polymer wasobtainedby measuring thefiowtime. of. asolution of. the polymerin 'dichlorobenzotrifluori'de'at. 140 C. The.specific, viscosity is defined. as follows:-

where is is now time-of-the solution-in seconds;- toisv thefiow time:of-thesolvent, and. 0 equals: the. concentration. grams/ -m1. ofsolvent. By knowing the specific viscosity, it is possible to correlatethis with the no strength temperature ofvthe polymer. The no strengthtemperature isv defined as the temperature PC. at whieh'a. molded pieceof polymeric chlorotrifiuoroethylenehavi'ng a cross sectional. area of T3 square will fall apart from its own weight and can be 76'; usedasa'measure of molecularweight. The re-' lationshipi of thespecificlviscosity to no strength temperature is shown in thefollowin'g:table: v I,

No Strength Temperature, 3C I N In this example several samples of theiormulation'found in sample Bf'of Example 1 were prepared lwith theexception that the;cata,1yst, tertiary. butyl perbenaoate, was employedin varying per cents thereof basedon the weight of;.the monomer. Theformulations were allowed toreact at,25 C(forld hours with agitation, atthe end of which time the per cent. conversion of. the monomer topolymer and the quality of the polymer were determined. The followingTable VI illustrates the eiTect of varyingthe percentage of catalyst,specifically the percentage (by weight The effect of varying thepolymerization temper-ature is described in this example. Moreparticularly, a mixture of ingredients comprising 75 partschlorotrifluoro ethylene, 545 parts water, 0.03part sodium bisulfite,0.12 part solublejron .phosphateand tertiary butyl perbenzoateing-thepercentages described in the following Table VII were charged to apressure reactor and the mixture of ingredients caused to react withagitation atv the temperatures and for the times disclosed in theaforementioned Table VII. l At the end of the stipulated time the percent conversion of the monomer to the polymer was determined as well asthe specific viscosity 115p.

Table vii 0.05% CATALYST Percent Time r 0 21 5 "In 0.04% PEROXIDE 0.02%PEROXIDE n will be noted that the temperature at which 10 the reactionis conducted is a controlling factor in the molecular weight of theproduct.

EXAIVIPLE 9 Ferric benzoate was disclosed previously as being highlyeffective in the system for polymerizing chlorotrifluoroethylene.However, it has been found'sensitive to pH efiects as illustrated inthis example, and. for this reason pH control should be carefullyexercised within the range described previously. A mixture ofingredients comprising 12.5 grams chlorotrifiuoroethylene, 25 gramswater, 0.02 gram sodium bisulfite, 0.002 gram ferric benzoate[Fe(CsH5CO2)3], and 0.012 gram tertiary butyl perbenzoate were chargedto a pressure reactor and the mixture of ingredients was; caused toreact 10 hours at 25 C. under a variety of conditions in which the pH ofthe 'systemwas variedby the introductionv of small amounts of -0.0l NKQH'. The following Table VIII shows the-per cent conversion of themonomer to the polymer as a result of the variation of the KOH. p M pTabz'e'vm h Percent Conversion As pointed out previously the heavy metal.eompound constituting part of the redox. system must be soluble in,themonomer. This can be effected; either by using an'originallymonomersoluble' 'heavy metal compound or forming "a monomeresolubleheavy metal compoundin situ by complexing; anoriginally,monomer-insoluble heavy; metal compound with a solubilizingagent. for, example, citric acid,etc. This example illustrates, theeffect of using both originally monomer-soluble heavy metal compoundsand originally monomer-insoluble heavy metal compounds inthepolymerization of chlorotrifluoroethylene. More particularly, amixture of in gredients comprising 25 parts water, 12.5 }"partschlorotrifluoroethylene, 0.02 part sodium bisulfite, 0.0125 parttertiary-butyl perbenzoate', and an amountof an iron salt disclosedinthe table below equivalent to 0.005- partsoluble iron phosphate, werecharged toa pressure reaction vessel, the vessel closed and heated withagitation under autog'enous pressure for about 16 hours at around 25 'C.At'the' end of this time the vessel was opened and the per centconversion of the monomerto. polymer'was determined in each case; 'Inthefollowin'g'table .th'eresults of these per: cents conversion aredisclos'ed'ior the respective heavylmetal compounds employed in thereaction. "It will be apparent from the table that where an originallymonomer-insoluble heavy'metal compound was employed the per centconversion was low. However, when an originally monomer-soluble heavymetal compound was employed or where the monomer- -insoluble heavy metalcompound was 'modified'by theaddition of a solubilizing agent, forexample,

citric acid, the conversion of the monomer to polymer'was high.

Fetiaeraaoa Table 1X 1 Iron Compound gg g Solublelron Phosphate." 90F82(S 003 91301804 241110 13 FeSO4(N 4)2SO4.6H2O -10 F6504]? 20"; J 15FeS O4.7Hz+0.'0ll2 part citric acid i. 87. 5 Fez(s()4)a .32 Fe(SO4)a+0.002 part citric acid 7,0 Fe(Stearate a .83 Fe(bensoate);l- 89Fe t acetyl acctonate)z 57 acetyl acetonateh J. 7B

topolyr'ner. lt willpof course, be apparent to those skilled 'in' theart-that other conditions of reaction as I I EXAMPLE 11 This exampleillustrates three runs in which large amounts of ingredients wereemployed simulating production conditions. The ingre- .dients describedin Table X were chargedto a 30gallbng1ass-lined Pfaudler autoclave eqipped. with an anchor stirrer revolving at 150 R. P. and having a keybattle. The time and conditions of reaction, as well as the per centconversion and specific viscosity of the polymer, are shown From theforegoing-itwvill' be apparent that I have discovered a method formaking'polymeric chlorotrifluoroethylene easily and rapidly, and

--usingrelatively low pressures of theorder of from about 30 to1-15-'p'.-'s. i. "I'he conversion to polymer is highand "the productobtained has outstanding'properties'a The fact that'my combination ofingredients and conditions was able to produce'the results describedcould in no way have been predicted sincethe omission of any of theingredients or conditions in my system gave substantially poorerconversions of the monomer well as different inodiflying ingredientsother than thoseused in the foregoing examples may be employedwithoutdeparting from the scope of the invention. I Many examples ofsuch modifying ingredients. as, for example, catalysts, members of theredox system and monomer-towater ratios which may be employed,etc.,..have

.beengiven-ipreviously, The polymers obtained in'accordance with my.olaimedprocess are tough and have high'fsoftenin points; In addition,many of the polymers-do not softentoa rubbery solid under a pressure of'75 p. s. i. up to temperatures of about 225L235 C. andare quite stable.

cause of their heat stability .atelevated tem- :peratures, they'areadvantageously employed as gaskets and valve packingswhere othermaterials cannot withstand the corrosive attack or elevatedtemperatures. Electrical conductors of all sorts, such as wires, motorarmatures and cables can be insulated with polymericchlorotrifluoroethylene, such insulated conductors being particularlyuseful because of the inertnes's of the insulating polymers.

Polymeric chlorotrifiuoroethylene has been found to be highly suitableas insulation for electrical conductors in which the surface beneath andimmediately adjacent the polymer is an aluminum type surface. Electricalconductors of this type are more particularly disclosed and claimed inthe copending application of Edward J. Flynn 'and'Gerald W. Young,Serial No. 54,63fiyfiled October 15, 1948, and assigned to the sameassignee as the present invention.j

If desired, dispersions of the polymer or solutions thereof maybeused'to coat and impregnate various fillers such as asbestos, glassfibers. aluminum powders, or sheetsor hard surfacesof various materialsas, for example, metal molds, glass cloth, asbestos cloth, etc. Suchtreated sheet materials may 'be molded under heat and pressure to obtainuseful objects. In the case of the treated sheets, the latter may besuperposed on each other and molded to give laminated panels havingoutstanding heat resistance and good electrical properties.

What I claim as new and desire to secure by Letters Patent of the'UnitedStates is:

1. The process forobtaining'polymeric chlorotrifluoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifluoroethylene, (b)water, the ratio of water to monomer on a weight basis being above 1 tol, ('c') an organic gperoxide polymerization catalyst for (a), (d)a'heavy metal compound whoseme'tal ion is capable-0f existing in atleast two valence states and which compound is soluble in thechlorotrifiuor'oethylene, and '(e) "a water-soluble reducing agent forthe heavy metal ion,- and (2) efiec'ting reaction under autogenouspressure between the ingredients at a pH of from about 2.3 to 4.0 'at atemperature below 35 C. for atime sufficient to effect polymerization ofthe monomer to polymeric chlorotrifiuoroethylene.

2. 'The' process for obtaining polymericchlorotrifluoroethylene having asoftening point above 220 0., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifiuoroethylene, (b)water, the ratio of water to monomer on a weight basis being above 1 to1, (c) an organic peroxide polymerization catalyst for (a), (d) asoluble iron phosphate which is soluble in the chlorotrifluoroethylene,and (e) a water-soluble reducing agent for the iron ion, and (2)effecting reaction under autogenous pressure between the ingredients ata pH of from about 2.3 to 4.0 at a temperature below 35 C. for a timesufiicient to effect polymerization of the monomer to polymericchlorotrifluoroethylene.

3. The process for obtaining polymeric chlorotrifluoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifluoroethylene, (1))water, the ratio of water to monomer on a weight basis being above 1 to1, (c) an organic peroxide polymerization catalyst for (a), (d) an ironbenzoate which is soluble in the chlorotrifluorocthylene, and (e) awater- 'soluble reducing agent. for the" iron ion, and

1(0)" an organic peroxide polymerizationfc 253 to 4.0 at a temperaturebelow-35 o. for a' time sufficient to efiect polymerization of themo'nom'er to polymeric bhlorotiifiuoroethyln.

Thep'roc'e'ss for obtaining polymeric chlomtrifluoroethylenehavingasoftening point above 220 C; which process comprises (1) fformi-ng asuspension of ingredients comprising ((1) "chloro trifluoroethylene,(2)) water; the'ratio of' water to monomer on a weight basisbein'g'abovel'to 1,. (c) an organic peroxide polymerization catalyst for(d), (d) a mixture of iron sulfate and citric acid which is soluble inthe chlorotrifluoroeth ylene, and (-e) a water-soluble reducing agentfor the iron ion, and (2) effecting reaction 'u'ndei autogenous pressurebetween the ingredients' at a pH of from about- 2.3 to 4.0 at atemperature below 35 C. for a time sufficient to effect polymerizationof the monomer. to polymeric chlorotrifluoroethylene.

5. The process for obtainingpolymeric chlorotrifluoroethylene having asofteningpoint 'abov'e 220 C., which process comprises (1). forming asuspension of ingredients comprising (a) hlorotrifluoroethylene, (b)watenl the ratio ater tojmonomer on a weight basis'bjeing above 1 for(a), (d) an "iron stearate which is soluble in thechlorotrifluoroethylene, and (e) a watersoluble reducing agent for theiron ion,.,and (2) effecting reaction under a'utogenouspressure betweenthe ingredients at a pH of from about 2.3; to 4.0 at a temperature below35 C. for a time sufficient to effect polymerization of the monomer topolymeric chlorotrifiuoroethylene.

The process for obtaining polymeric chlorotrifiuoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotriiiuoroethylene, (b)water, the ratio of water to monomer on a weight basis being above 1 tol, (c) an organic peroxide polymerization catalyst for- (a), (d) a heavymetal compound whose metal ion is capable of existing in at least twovalence states and which compound is soluble in thechlorotrifluoroethylene, and (e) a watersoluble reducing agent for theheavy metal ion comprising sodium bisulfite, and (2) effecting reactionunder autogenous pressure between the ingredients at a pH of from about2.3 to 4.0 at a temperature below 35 C. for a time sufficient to efiectpolymerization of the monomer to polymeric chlorotrifluoroethylene.

'7. The process for obtaining polymeric chlorotrifluoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifiuoroethylene, (b)water, the ratio of water tomonomer on a weight basis being above 1 to1, (c) an organic peroxide polymerization catalyst for (a), (d) asoluble iron phosphate which is soluble in the chlorotrifluoroethylene,and (e) a water-soluble reducing agent for (d) comprising sodiumbisulfite, and (2) effecting reaction under autogenous pressure betweenthe ingredients at a2.pI-I of from about 2.5 to 3.5 at a temperaturebelow 35 C. for a time suflicient to eifect polymjrization of themonomer to polymeric chloro trifluoroethylene.

:8. The process for obtaining polymeric chlorotrifiuoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifluoroethylene, (1)),water, the ratio of water tomonomer on afweight basis being above l toi', (c) -an organic peroxide polymerization catalyst for-"(11); (d) anironbenzoate whichxis soluble in the chlorotrifluoroethylene, and ('e)*awatersoluble reducing agent for (d) comprising sodium bisulfite, and (2)effecting reaction under autogenou's' pressure between the singredients.at .a; 'pH of from about 2.5 to 3.5 at a-temperaturezbelow C.;"for'atime sufficient to effectpolymerization of. the monomer to polymericchlorotrb fiuoroethylene. I I :9. The=process for obtaining polymericchlorotrifluoroethylene having'asoftening point above 220 C., whichprocess comprises (1) 'forming a suspension of ingredients comprising(it) chlorotrifluoroethylene, (b) water, the -ratiodo'f water to-monomeron a weight basis being abovelfto 1*, (c): an "organic peroxidepolymerization' cataly'st for (a), .(d) a mixtureof iron sulfateIa-ndcitric "acid: whichlis soluble the chlorotrifiuoroethyle .ene. and '(e)anwater soluble' reducing" agent for (d) comprisingsodiurnizlbisulfite,and '(2) effectingoreaction? under autogenous pressure. between theingredients atapH of from about 2:57 110 3.5 "at a temperature below35iC. for a timessumcient to; eilect polymerization 'of' themonom'er topolymeric"chlorotrifiuoroethylene. 1 10; The processrssior. obtaining"polymeric chlorotri'fluoroethylerie having: a" softening point above220'C;,:which process comprises (1) .forming a suspension ofingredientsncomprising (a) -Ch1OI.OfiliOI'O8l}hy18I16,'i(ab); water,"the static l of Water to m'onom'eron a weight basiscbeing about 1 to 1,(c) an organic peroxide polymerization catalyst for (a), (d) an ironstearat'e which is soluble in the chlorotrifluoroethylene, and (e) awater-soluble reducing agent for (d) comprising sodium bisulfite, and(2) effecting reaction under autogeneous pressure between theingredients at a pH of from about 2.5 to 3.5 at a temperature below 35C. for a time sufficient to effect polymerization of the monomer topolymeric chlorotrifluoroethylene.

11. The process for obtaining polymeric chlorotrifiuoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifluoroethylene, (b)water, the ratio of water to monomer on a weight basis being above 1 tol, (c) tertiary butyl perbenzoate, (d) a soluble iron phosphate which issoluble in the chlorotrifiuoroethylene, and (e) a water-soluble reducingagent for (d) comprising sodium bisulfite, and (2) effecting reactionunder autogenous pressure between the ingredients at a pH of from about2.5 to 3.5 at a temperature of from about 0 to 30 C., for a timesufficient to effect polymerization of the monomer to polymericchlorotrifiuoroethylene.

12. The process for obtaining polymeric chlorotrifluoroethylene having asoftening point above 220 C., which process comprises (1) forming asuspension of ingredients comprising (a) chlorotrifiuoroethylene, (12)water, the ratio of water to monomer on a weight basis being above 1 to1, (c) tertiary butyl perbenzoate, (d) an iron benzoate which is solublein the chlorotrifluoroethyltrifinoroethylene having a softening pointabove 2-20 0.; which process comprises v( l) forming a suspension ofingredients comprising (a) chlorotrifluoroethylene, (b) water, the ratioof water totmonomer on a weight basis being above 1 to 1-, (c) tertiarybutyl perben'zoate, (d) axmixture of iron sulfate and citric acid whichis soluble in the chlorotrifluoroethylene, and (e) 'awater-solublereducingflagent for (d) comprising sodium bisillfiteg and (2) effectingreaction under autogenous pressure between the ingredients at a .pHofztrhm about 2.5 to 3.5 at a temperature 'of from about 0 to 30 "C.,for ati'me sufieient toeffect polymerization of the monomer to polymericchlorotrifluoroethylene. t

14. The "process for obtaining polymeric chlorotr'ifluoroethylene havinga softening point above 220201, which process comprises (1) forming'asuspension of ingredients comprising (a) chlorotrifluoroethylene, (17)water; the ratio of water .to'monom'er on a weight basis being above "1,to) tertiary butyl perbenzoate,-y(d) an iron .stearate which. is solublein the chlorotritiuoroethylene, and '(e) -a water-soluble reducing agentfor (d) comprising sodium bisulfite, and

(2) feffecting'reaction'under autogenous pressure between theingredients-at a pH. of from about 2.5 to 3.'5at a temperature of fromabout 0-to 30 0., for a time suflic'ient to eficct polymerization of themonomer to polymeric chlorotrifiuoroethylene." v 1 15. "The process forobtaining polymeric chlorotrifluoro'ethylene having a softening pointabove 16 220.-C., which processcomprises (1 forming-a a suspension ofingredients comprising (a) chlorotrifluoroethylene; (b) water, the ratioof water to monomer on a weight basis being above 2 to l, (c) from 0.01to 0.5%, by weight, tertiary butyl perbenzoate, (d) a soluble ironphosphate which is soluble in the chlorotrifluoroethylene and which ispresent, by weight, in an amount equal to from 0.01 to-0.5%, the weightof (c) and (d) each being based on the weight of the monomericchlorotrifiuoroethylene, and (e) sodium bisulfite equal to from 001 to0.5% of the weight of the water, and (2) effecting reaction underautogenous pressure between the ingredients at a pH of about 2.5. to 3.5at a temperature of from about 0" to 30 0., for a time sufiicient toeffect polymerization of the monomer to the polymericchlorotrifluoroethylene.

. GEORGE F. ROEDEL.

REFERENCES CITED The following references are of record in the file ofthis patent: I

3 UNITED STATES PATENTS France Mar. 27, 1936

1. THE PROCESS FOR OBTAINING POLYMERIC CHLOROTRIFLUOROETHYLENE HAVING ASOFTENING POINT ABOVE 220* C., WHICH PROCESS COMPRISES (1) FORMING ASUSPENSION OF INGREDIENTS COMPRISING (A) CHLOROTRIFLUOROETHYLENE, (B)WATER, THE RATIO OF WATER TO MONOMER ON A WEIGHT BASIS BEING ABOVE 1 TO1, (C) AN ORGANIC PEROXIDE POLYMERIZATION CATALYST FOR (A), (D) A HEAVYMETAL COMPOUND WHOSE METAL ION IS CAPABLE OF EXISTING IN AT LEAST TWOVALENCE STATES AND WHICH COMPOUND IS SOLUBLE IN THECHLOROTRIFLUOROETHYLENE, AND (E) A WATER-SOLUBLE REDUCING AGENT FOR THEHEAVY METAL ION, AND (2) EFFECTING REACTION UNDER AUTOGENOUS PRESSUREBETWEEN THE INGREDIENTS AT A PH OF FROM ABOUT 2.3 TO 4.0 AT ATEMPERATURE BELOW 35* C. FOR A TIME SUFFICIENT TO EFFECT POLYMERIZATIONOF THE MONOMER TO POLYMERIC CHLOROTRIFLUORETHYLENE.